The purpose of this study is to investigate the psychological, physiological and behavioral characteristics of children exposed to substance abuse. Children exposed to substances in utero are being compared to children living in drug environments as well as children from similar socioeconomic backgrounds. The children currently participating in the study are boys between the ages of 7 and 12 years of age. Assessments being conducted include cognitive processing tasks of sustained attention, psychometric tests (e.g. IQ), heart rate reactivity, evoked-response potentials (ERP), and fine motor control. Additionally, maternal reports of childhood health and behavior are being collected. Initial findings indicate that boys exposed to opiates in utero may have deficits in physiological reactivity to attentional demand. While boys living with drug using mothers and socioeconomic matched control boys responded to attentional demand with characteristic heart rate responses, opiate exposed boys did not. Additionally, the ERP's of opiate exposed boys were found to differ from those of the control boys. Currently, these initial findings are being replicated with a second cohort of boys between 7 and 12. Additional incentive and activity measures have been included to assess motivational and motor activity influences on observed changes in heart rate responses to attentional demand. The initial findings of differences in heart rate reactivity among children exposed to opiates in utero suggest central nervous system changes which may influence their approach to difficult and attention demanding tasks. Such a biological vulnerability could place these children at higher risk for school and learning problems.